Sensorimotor Oscillations Prior to Speech Onset Reflect Altered Motor Networks in Adults Who Stutter

Abstract

Adults who stutter (AWS) have demonstrated atypical coordination of motor and sensory regions during speech production. Yet little is known of the speech-motor network in AWS in the brief time window preceding audible speech onset. The purpose of the current study was to characterize neural oscillations in the speech-motor network during preparation for and execution of overt speech production in AWS using magnetoencephalography (MEG). Twelve AWS and 12 age-matched controls were presented with 220 words, each word embedded in a carrier phrase. Controls were presented with the same word list as their matched AWS participant. Neural oscillatory activity was localized using minimum-variance beamforming during two time periods of interest: speech preparation (prior to speech onset) and speech execution (following speech onset). Compared to controls, AWS showed stronger beta (15–25 Hz) suppression in the speech preparation stage, followed by stronger beta synchronization in the bilateral mouth motor cortex. AWS also recruited the right mouth motor cortex significantly earlier in the speech preparation stage compared to controls. Exaggerated motor preparation is discussed in the context of reduced coordination in the speech-motor network of AWS. It is further proposed that exaggerated beta synchronization may reflect a more strongly inhibited motor system that requires a stronger beta suppression to disengage prior to speech initiation. These novel findings highlight critical differences in the speech-motor network of AWS that occur prior to speech onset and emphasize the need to investigate further the speech-motor assembly in the stuttering population.

EEG Mu ( µ ) rhythm spectra and oscillatory activity differentiate stuttering from non-stuttering adults

“…The findings were thought to reflect the transfer of timing to sensorimotor information through fluctuations in corticobasal-ganglia and thalamocortical circuits, demonstrating how basal ganglia circuits can contribute to forward models by coding changes in predictive timing of auditory information (Arnal 2012; Arnal & Giraud 2012). Stuttering-related differences in β oscillations recently have been found in children (Etchell et al, 2016) and adults (Mersov et al, 2016). Third, selection and inhibition processes modulate and stabilize sensory experience and fluid movements operate through basal ganglia circuits (Buzsaki, 2006;Klimesch et al, 2007;Okun and Lampl, 2008;Jensen and Mazaheri, 2010) and can be measured by changes in α fluctuations across motor regions (Bonstrup et al, 2015).…”

Increase in Beta-Band Activity during Preparation for Overt Speech in Patients with Parkinson’s Disease

“…Mersov et al (2016) studied brain rhythms of fluent speakers and adults who stutter using magnetoencephalography before and during cued overt reading of words in a carrier phrase. During speech preparation, a decrease of β-power (in this study: 15–25 Hz) was found in the bilateral cuneus of fluent individuals.…”

Het gebruik van magnetoencefalografie als hersenbeeldvormingstechniek voor het bestuderen van neurale processen bij ontwikkelingsstotteren

“…We analyseerden en vergeleken modulatie in neurale oscillaties tijdens spraakvoorbereiding in een group van AWS en typisch vloeiende sprekers (Mersov et al, 2016). De AWS lieten zowel sterkere bèta-onderdrukking als bèta-synchronisatie zien in de bilaterale mondmotorcortex.…”